The use of aspiration catheters for a variety of medical procedures has been well established, including the use of aspiration catheters for removing blood, obstructions, thrombus, or debris from blood vessels. This can be accomplished using manual means, like a hand pump or syringe, or mechanical means such as mechanical pump. Aspiration catheters have taken the form of simple single-lumen catheters or more complicated multi-lumen catheters. Perhaps the most common aspirations performed in blood vessels are those involving aspirations of thrombus through single lumen tubes that are opened to atmospheric pressure. These aspirations are commonly performed during surgery, or done percutaneously during coronary or peripheral interventions.
One problem common to all aspiration catheters is the natural tendency of the viscous blood to resist flow in channels, especially when these channels are small and long as they are with typical catheters, see e.g., U.S. Pat. No. 6,152,909 (Bagaoisan et al.). This resistance is termed ‘viscous loss’ and higher viscosity fluids or longer catheters require higher pressures to maintain sufficient flow, see e.g., U.S. Pat. Nos. 5,833,644 and 6,022,336 (Zadno-Azizi et al.). This becomes a difficult challenge when using aspiration catheters inside blood vessels since the pressure differential available to move the blood is never greater than atmospheric pressure and is often quite lower. Therefore, optimizing the channel size or ID of the catheter while maintaining a small OD of the catheter becomes a primary design requirement. Given the physical constraints of this problem, effective aspiration catheters are limited to ID's approximating 1mm or larger for catheters longer than 100 cm. Hemodialysis catheters readily overcome this problem with large ID's, however these catheters are very short, see e.g. U.S. Pat. No. 6,568,329 (Mahurkar) and U.S. Pat. No. 5,195,962 (Martin et al.). Longer lengths of this catheter design would not function in an intra-thoracic procedure.
Another problem common to blood vessel catheters is maneuverability. That is, the ability for the catheter to be advanced into small tortuous vessels with ease. This requires small catheter diameters (and flexible materials), which is directly at odds with optimizing aspiration flow. In aspiration catheter constructions that involve additional functions beyond simple aspiration and thus require multiple lumens, this is especially problematic.
An aspiration catheter that is capable of being advanced into distal locations and directed beyond multiple branch points in the vasculature while being capable of suitable aspiration volumes would be desired.